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Abstract:

Alternative methods of designing, developing and manufacturing optical
elements and assemblies are provided which enable improvements in
effectiveness and efficiency. Subtractive processes using lasers or other
tools are utilized to create embedded void spaces that provide reflecting
walls within internally reflective optical elements. The designs have
advantages in cost, reduced development time, and performance. Light from
multiple light sources can be mixed and collimated. Some embodiments
provide the ability to integrate a large number of internally reflective
optics into a single component and very large components can be made.
Embodiments of the invention are designed for manufacturing and can be
made without molding tooling.

Claims:

1. A method for producing an optical element comprising: a) providing an
optical element design which includes one or more embedded internally
reflective surfaces; b) creating a cutting pattern or program to serve as
instructions for a localized subtractive process; c) Using said localized
subtractive process to remove material from a light transmissive volume
in a manner which creates air voids within said volume whereby said air
voids provide internal reflecting walls within said light transmissive
volume.

2. The method of claim 1 wherein said localized subtractive process
traces said cutting pattern onto the surface of said light transmissive
volume; further controlling the incident angle of the laser to the
surface of said light transmissive volume thereby controlling the
intersecting angle of the resulting reflecting wall with the surface of
said light transmissive surface.

5. The method of claim 1 wherein said localized subtractive process is
water jet cutting.

6. The method of claim 1 wherein said light transmissive volume is a
sheet.

7. The method of claim 1 wherein said light transmissive volume is
acrylic.

8. The method of claim 1 wherein a fastening feature is additionally
fabricated with a localized subtractive process.

9. The optical element of claim 8 wherein a fastening features is located
in an optically isolated region.

10. The method of claim 8 wherein the fastening feature is a hole, tab,
clip, or channel.

11. The method of claim 1 wherein said localized subtractive process is
performed with the light transmissive volume at an annealing temperature.

12. The method of claim 1 wherein said transmissive light volume is
annealed after said localized subtractive process is performed.

13. The method of claim 1 whereby said localized subtractive process is
performed on a moving light transmissive volume.

14. The method of claim 13 whereby said moving light transmissive volume
is engaged in a polymer extrusion process or its subsequent following
processing steps.

15. The method of claim 1 wherein said optical element is a collimating
optical element for a lighting application.

16. The method of claim 1 wherein said reflecting wall is subsequently
coated with a material of refractive index different than the material of
the light transmissive volume.

17. An optical element suitable for manufacture by the method of claim 1
whereby; a) one or more internal reflecting walls are embedded within
said optical element and; b) each embedded reflecting wall extends to at
least one surface.

18. The optical element of claim 17 wherein every surface location of
each reflective wall either intersects or is tangent with a line that can
be extended from outside the optical element without passing through the
light transmissive volume.

19. A method for developing an optical element comprising the steps; a)
providing an optical element design which includes one or more internally
reflective surfaces; b) creating a cutting pattern or program to serve as
instructions for a localized subtractive process; c) Using said localized
subtractive process to remove material from a light transmissive volume
in a manner which creates voids within said volume whereby said voids
create reflective walls within said light transmissive volume. d) Testing
said optical element to compare actual performance to targeted
performance; further using said test to direct process to either i)
return to said step a to redesign said optical element; ii) return to
said step b to redo said instructions; iii) return to step c to redo said
localized subtractive process; iv) proceed to production manufacturing;
e) Repeating as needed steps a through d until targeted performance is
achieved.

20. The method of claim 19 whereby no molds are required to fabricate
reflecting walls.

[0002] The market for the mass production of lenses for new highly
efficient and cost effective optic solutions, such as those involving
light emitting diodes (LEDs), is expected to grow significantly in the
near future as they replace older, less efficient lighting systems. In
order to meet the rising demand, suppliers are looking to develop new
ways of manufacturing lenses on a larger scale.

[0003] TIR (total internal reflection) collimating lenses are commonly
used for applications such as LED lighting and are typically produced
using injection molding processes. Injection molding, the most common
precision method for mass production of optical elements, provides means
to produce lenses in high volume but is subject to high costs and long
lead times associated with the making of required tooling. Additionally,
injection molding equipment requires significant capital investment and
requires significant energy to operate. Some disadvantages of this
process are expensive equipment investment, potentially high operating
costs, and the need to design parts in such a manner that they can be
non-destructively separated from tooling after molding. Tooling
restrictions of molded parts limit the designs possible with molded
parts.

[0004] There is need for alternative design and manufacturing methods
which can shorten development time of new optical components, provide
lower fixed and operating costs, and provide capabilities to for new
types of designs.

SUMMARY

[0005] Alternative methods of designing, developing and manufacturing
optical elements and assemblies are provided which enable improvements in
effectiveness and efficiency. Subtractive processes using lasers or other
tools are utilized to create embedded void spaces that provide reflecting
walls within internally reflective optical elements. The designs have
advantages in cost, reduced development time, and performance. Light from
multiple light sources can be mixed and collimated. Some embodiments
provide the ability to integrate a large number of internally reflective
optics into a single component and very large components can be made.
Embodiments of the invention are designed for manufacturing and can be
made without molding tooling.

DESCRIPTION OF FIGURES

[0006] FIG. 1 is a perspective view of a linear embodiment of an optical
collimating assembly containing an optical collimating element fabricated
with a laser cutting process.

[0007] FIG. 2 is a cross-section view of a linear embodiment of an optical
collimating assembly containing an optical collimating element fabricated
with a subtractive laser cutting process. Fasteners are shown mounted
through the optically isolated region.

[0008] FIG. 3 is a cross-section view of a linear embodiment of an optical
collimating assembly containing an optical collimating element fabricated
with a subtractive laser cutting process. Included is a light redirecting
layer with half sphere shaped features.

[0009] FIG. 4 is a cross-section view of a linear embodiment of an optical
collimating assembly containing an optical collimating element fabricated
with a subtractive laser cutting process. Included is a light redirecting
layer with prism shaped features.

[0010] FIG. 5 is a prior art illustration of a typical LED optic assembly

[0011] FIG. 6 is a prior art picture of commercial LED fixture with
typical LED optic assembly

[0012] FIG. 7 is a prior art picture of a commercial liner LED fixture
with typical LED optic assembly.

[0019] FIG. 14 is an overhead view of an example laser fabrication process
configured for high volume production.

[0020] FIG. 15 is a flowchart showing the development cycle associated
with the development of optical elements to be manufactured by a
subtractive voiding process which produces TIR features.

[0021] FIG. 16 is a flowchart showing the development cycle associated
with the development of optical elements to be manufactured by an
injection molding process as is typical of current commercial LED lenses.

[0023] In order to promote an understanding of described manufacturing
methods, reference will now be made to the exemplary embodiments
illustrated in the drawings, and descriptive language will be used to
detail the same. It will nevertheless be understood that no limitation of
the scope of the invention is thereby intended. Any alterations and
further modifications of the inventive features manifested herein, and
any additional applications of the principles of the invention as
depicted herein that would occur to one skilled in the art are to be
considered within the scope of the invention.

[0024] Embodiments of the invention will now be described with reference
to the accompanying figures.

[0025] FIG. 1 is a perspective drawing of a linear embodiment of a
collimating optical assembly. The optical assembly includes a linear
collimating optical element 100, a light source board 200, and optionally
refractive lenses 160. The light source board 200, its surface 210, and
its associated lighting sources 220 are aligned such that the collimating
optical element 100 may be inserted onto the light source board. As
shown, both the spacing for lighting source on the collimating optical
element opening 110 and the spacing between the light sources 220 on the
lighting strip are in a linear equally spaced apart relationship. In an
alternative embodiment, the spacing between each lighting source 220 is
not equidistant. The collimating optical element 100 rests on top of the
light source board 200 and may be fixated by any reasonable means, such
as on the outer edges of the collimating optical element 100 and light
source board 200. Alternatively, the collimating optical element 100 may
be molded or otherwise bonded to the light source board 200. In some
embodiments, the collimating optical element can be configured to lay
flat upon the light source board 200 in a stable manner without
additional mounting structures as commonly used with conventional
secondary optical lenses. The conventional design of a molded TIR optical
lens, such as the reference lens shown in FIG. 5, typically produces a
lens which easily tips over or becomes detached from its intended light
source due to a small contact area with the LED board and a top-heavy
design resulting from increasing width vs. distance from the LED board.
Traditionally, a lens holder is used to mechanically stabilize and fasten
individual LED lenses. FIG. 5 shows a conventional optical assembly of
individual collimating lenses. In contrast, in the present embodiment of
the invention, an integrated optic can be mechanically stabilized and
aligned with respect to the light sources by fastening to or through an
optically isolated region 180 of the optical element as shown in FIG. 2.
This allows the entire integrated optic to be stabilized and fastened in
a light fixture with one process while avoiding interference with the
primary optical output path of the assembly. Typically, at least one void
space and reflective wall are positioned between a light source and an
optically isolated region. An optically isolated region is one which at
least one void space and reflective wall is placed between a light source
and the region.

[0026] FIG. 1 illustrates a linear embodiment of the invention that can be
used in similar applications to conventional linear LED light fixtures,
such as the one shown in FIG. 7. Many configurations are possible for
producing voids within the optical element that create reflective walls.
Embodiments can be fabricated with the use of a CO2 laser, which produces
narrow voids with a range in width of 0.1-2 mm, more ideally 0.5-1.5 mm
and most preferably less than approximately 1 mm wide that can be
fabricated in precise patterns. For example, circular cuts with a CO2
laser can be used to create void spaces 130 that produce tubular
reflecting walls 140 encircling individual light sources as shown in FIG.
8 and FIG. 9. Alternatively, concentric voids creating angled concentric
reflecting walls 140 can be fabricated in lenses to form collimating
concentric rings as shown in FIG. 10 and FIG. 11. Either of these
alternatives could be utilized in a LED fixture application such as a
downlight.

[0027] Shown in FIG. 1 is a linear collimating optical assembly embodiment
that is particularly adapted for directly lighting or illuminating a
space or target illumination zone. The collimating optical element 100 is
mounted to a base member, for example a LED light strip with an array of
LEDs, so that light emitted from the lights on the light strip is
directed through the shaped opening 110 on the collimating optical
element when the lights are lit. The collimating optical element 100 is
constructed from a rigid translucent material such as acrylic or
polycarbonate. The light strip may be comprised of an opaque material
with a white surface to facilitate scattering of incident light toward
the output surface. If it is desired to have some light infiltration
through the back side of the strip, a translucent or transparent material
may be optionally employed. The optical collimating element 100 comprises
a series of linear collimating optic features integrated into the
collimating optical element 100. Un-collimated light diverging from the
lighting source enters the optical collimating lens through the shaped
opening 110 and is focused into rays of light significantly more normal
to the output surface 10.

[0028] The shaped opening may be of any practical size or shape, as
illustrated in FIG. 1, to account for the varying light source packages
that may be used with a collimating optical element, as will be readily
apparent to those skilled in the art. Light distribution from the optical
assembly is influenced by the angle of the reflecting walls 140 of the
linear collimating optical element 100. The reflecting walls 140 utilize
a void 130 embedded within the lens that may remain an air space in final
use or alternatively be filled with a substance of refractive index
differing from that of the lens substrate. Prototype embodiments have
been fabricated with the use of either 40-watt or 60-watt CO2 lasers,
which effectively removed a channel of material from a sheet of
commercially available Acrylite FF extruded acrylic sheet manufactured by
Evonik Industries. The staggered pattern of angle cuts into the sheet
produced sufficient air interface structures for collimation while
maintaining the physical integrity of a single optic component.

[0029] Optionally, it is possible to fabricate additional holes or
miscellaneous cutouts in the collimating optical element without
interfering with the optical path. These can be used to facilitate the
use of fasteners to hold the collimating optical element and circuit
board to each other or other components such as mounting frames,
housings, heat sinks, etc. Optionally, reflectors can be cut continuously
through the collimating optical element substrate to produce a smaller
optic with an angled edge.

[0030] FIG. 1 illustrates a collimating optical assembly embodiment with
reflecting walls 140 that are internally reflecting. The reflective walls
140 function as TIR optics within a critical angle of total internal
reflection determined by Snell's law as

θ crit = arcsin ( n 2 n 1 sin θ 2
) = arcsin n 2 n 1 ##EQU00001##

where θ2=90°. η2 equals the refractive index
of the light transmissive matrix, 1.49 in the case of acrylic.
η1 equals the refractive index of the void material, 1 in the
case of air.

[0031] FIG. 1 and FIG. 2 show views of a linear embodiment of an optical
collimating assembly containing an optical collimating element fabricated
with a subtractive laser cutting process. Fasteners 181 are shown mounted
through the optically isolated region 180. A light source 220 is mounted
to a light source board 200 and disposed within a shaped opening 110. The
surface of the shaped opening serves as a refracting wall 120 in the
optical design. Void spaces 130a and 130b create reflecting walls 140a
and 140b respectively. Example light rays emitted from the light source
are traced as output path 1, output path 2, and output path 3. Output
path 1 is refracted by the refracting wall, reflected by the reflecting
wall, and subsequently emitted from the output surface 10. Output path 2
is emitted from the light source and passes directly through the shaped
opening. Output path 3 reflects off of the refracting wall before exiting
the shaped opening. A prototype of the embodiment of FIG. 1 was
fabricated and measured to have a collimated beam output with a full
width half maximum (FWHM) of 71 degrees in the y axis and 79 degrees in
the x axis. This compares with a FWHM of 140 in the y axis and a FWHM
angle of 130 degrees in the x axis with no collimating optical element.
Peak brightness was increased with the collimating optical element by
43%.

[0032] FIG. 3 and FIG. 4 are a cross-section views of linear embodiments
of an optical collimating assembly containing an optical collimating
element fabricated with a subtractive laser cutting process. Both
embodiments include a refractive lens 160 in the shape of a sphere to
increase collimation of light emitted through the shaped opening 110.
Other refractive lens shapes that improve collimation or light
distribution can be used in alternative embodiments. Half spheres, and
prisms are examples of alternative embodiment shapes.

[0033] A secondary light-redirecting layer 150 can be used to further
control light distribution. Examples of this include a diffuser or light
redirecting features positioned at or near the output surface, as
illustrated in FIG. 3 and FIG. 4. A secondary light redirecting layer may
be an integral part of the optical element or it may detachably mounted
to the collimating optical element or optically coupled to the
collimating optical element so that the path of light is further
directed. "Optically coupled" is defined herein as including the
coupling, attaching or adhering two or more regions or layers such that
the intensity of light passing from one region to the other is not
substantially reduced due to Fresnel interfacial reflection losses due to
differences in refractive indices between the regions. Optical coupling
methods include joining two regions having similar refractive indices, or
by using an optical adhesive with a refractive index substantially near
or in-between at least one of the regions or layers. Examples of
optically coupling include lamination using an index-matched optical
adhesive such as a pressure sensitive adhesive; lamination using a UV
curable transparent adhesive; coating a region or layer onto another
region or layer; extruding a region or layer onto another region or
layer; or hot lamination using applied pressure to join two or more
layers or regions that have substantially close refractive indices; or
solvent bonding a region or layer to another region or layer. A
"substantially close" refractive index difference is about 0.5, 0.4, 0.3
or less, e.g., 0.2 or 0.1. Optionally, the collimating optical element
may contain light scattering regions formed during the manufacturing of
the substrate material. Coextrusion or multi-shot injection molding are
examples of processes that can be used to produce combinations of
scattering and non-scattering regions. Alternatively, light redirecting
features can be fabricated onto the output surface of the optical element
by processes such as embossing.

[0034] Water jet cutting is an example of an alternative subtractive
process to laser cutting suitable for fabrication of voids and recesses
within the optical elements for some embodiments.

[0035] As an alternative embodiment the voids created to produce a light
reflective surface in an optical element may be filled with a material of
refractive index different from the starting substrate material and thus
function similarly but without an air gap void. For example water,
silver, gold, chromium, or copper could be used as a material to coat
and/or fill void spaces. Silver and gold are of particular interest as
they have a refractive index less than that of air and thus could produce
a larger critical angle of total internal reflection and effectively
allow for narrower reflector angles, more collimation, and fewer
efficiency losses from light emitted at low angles which do not
internally reflect. Chromium has a very high refractive index ˜2.97
which could be used to create a large refractive index difference at the
reflective interface. A thin layer with thorough coverage can be
sufficient to produce a refractive index mismatch between the deposited
material and the collimating optical element substrate material. Liquid
solution, vapor deposition, or atomic layer deposition coating processes
are example processes that can be used to produce a mirror type finish
without permanently filling the entire air gap void space. Acrylic (PMMA)
has a refractive index close to 1.49 and is a possible substrate material
for the collimating optical element. Polycarbonate is another example
lens substrate material and has a refractive index typically near 1.587.

[0036] One possible benefit of coating or filling the reflecting void
space is that it can thus be made resistant to changes in reflection
caused by the accumulation of water at the interface surface. This can be
important in some applications that involve outdoor exposure or water
condensing environments.

[0037] FIG. 13 illustrates the process of cutting an optical element from
a light transmissive substrate 40 by means of a high precision laser in
accordance with an embodiment of the present invention. The laser beam is
transmitted by means of a resonator, which amplifies and generates
certain types of beam profiles. A focused beam output 22, for example,
may be obtained by means of a laser with a focusing lens. The cutter uses
a computer to direct the focused laser beam 22 at the material to be cut,
for example, making embedded void space 130 cuts and complete cut outs
through the light transmissive substrate 40 to produce shaped openings
110 as well as cut outs, slots, and the outer perimeter shapes for panels
and tabs. In this process, if the light transmissive substrate 40 is
moving along a carrier, e.g. a table, the laser piece moves in the X and
Y direction of the workpiece and adjusts its height in the Z direction to
make the lens cuts. Each type of cut has a particular depth and shape,
and as such, each cut requires different operating parameters of the
laser cutter to accomplish such depths and shapes. The output of the
laser may be directed at the light transmissive substrate at a certain
incident angle 23 to make angled cuts as shown in the cross section views
of FIG. 2, FIG. 3, and FIG. 4. The angle of the focused laser beam output
with respect to the normal is dependent on the angle of the cut to be
made in the material for the lens. As the focused beam output cuts the
light transmissive substrate, the material may melt, burn, or vaporize in
accordance with an embodiment of the present invention, leaving an edge
with a high-quality surface finish. CO2 laser cutting of acrylic is
well known as capable of producing a very flat and smooth surface which
is usually preferred for an internally reflective optic. The rate at
which the laser moves along the axis' is dependent on the cuts to be
made. The relative movement between the workpiece on the carrier and the
laser beam is preferably induced by an adjustment device, which is driven
and adjusted by an adjustment control signal. The adjustment control
signal is generated from the computer controlling the laser cutting
process and is based upon the design of the lens. It is nevertheless also
possible for the laser piece to remain fixated and move in the X and Z
direction as the workpiece moves along the carrier. Furthermore, it is
also possible for the laser to only move in the X or Y direction as the
workpiece moves along the carrier. Alternatively the light transmissive
substrate may remain stationary during fabrication and the laser may be
moved in X, Y, or Z dimensions to direct the cutting pattern of the light
transmissive substrate 40.

[0038] Once the workpiece has been cut, post-processing operations may be
employed to the workpiece. Embodiments of the invention may thus include
holes, tabs, clips, channels or other specific fastening or mounting
structures. The integrated design of the optical element allows that the
optic itself can contain such features without significantly interfering
with the intended light distribution output from the optical element.
Additional post-processing operations may also include cooling of the
material, annealing, coating the lens with a diffusive material, or
performing thermal treatment on the lens by heating and rapid cooling,
induction heating, or laser heat treatment.

[0039] A step in the fabrication process of some embodiments is the
cutting of the light transmissive sheet to a desired length. An advantage
of some embodiments is that the lens may be cut from a sheet of light
transmissive material to any reasonably contemplated length or
configuration before or after localized subtractive processing of
reflective walls and refractive walls. For embodiments fabricated with a
continuous process such as shown in FIG. 14, cutting to piece size can be
done in-line with a laser after refractive and reflecting walls have been
fabricated.

[0040] One advantage of the present invention is its ability to easily
scale in volume. In one embodiment, the system and method of the present
invention integrates the mass production manufacturing techniques of
sheet extrusion with an inline cutting with one or more lasers of
multi-axis control to produce optical elements for applications such as
collimating lenses for LED light fixtures. Such a system includes a sheet
extrusion system for producing and processing light transmissive
extrudable thermoplastic materials, a laser cutter for cutting embedded
air voids, surface marks, holes, slots, panels, etc. into a selected
substrate, a ventilation system to remove heat and combustible gasses
from the cutting surface, and a computing system for controlling the
cutting process. Functionality of a laser will increase proportionally
with the number of axes of movement it has. For a basic embodiment a
laser can be mounted in at a desired angle in a stationary manner and
extruded sheet fed through to cut in the extrusion direction. Adding a
x-y gantry system will allow the laser to travel with and across the
extrusion flow direction. A 5 axes system will add tilt and rotation,
useful for making embedded collimating air interfaces planar or conical
in shape. In all cases, with a controller, the laser can be sychronized
to the direction and speed of the extrusion in order to cut precision
features laid out across the extruded sheet. Additionally, multiple
lasers can be controlled in a synchronized manner to simultaneously cut
different regions of moving sheet extrusion web.

[0041] The cutting of optical elements from the optical material is
optimally performed at a temperature greater than the annealing
temperature of the material being cut, where the material is stiff enough
not to deform during process handling, but soft enough to avoid the
accumulation of thermal stresses during high temperature laser processing
and the following cooling. As typical with sheet extrusion lines, the
extruded and laser cut material may pass through temperature control
zones to provide slow even cooling and the avoidance of warping during
cool down.

[0042] Some of the benefits realized from the invention include high
output efficiency, low production startup costs, low setup time, reduced
chance of warping of the material that is being cut, highly precise
lenses that are cost effective when either produced in low or high
quantities, and reduced product waste. The fully integrated lens
production system provides for uniformity in system components and
performance.

[0043] The system can be used to cut, engrave, and embed air voids within
materials in a wide variety of applications and industries. One or more
lasers can be configured as needed to match the cutting throughput with
extrusion line speed. Multiple lasers can cut in parallel with each other
or be positioned along the extrusion path to cut sequentially. The system
and method also allows for an extremely dense arrangement of lenses in a
sheet. Since the unused space can be reduced significantly, the method
produces an optically efficient area of nearly 100 percent.

[0044] The system and method of the present invention, for example, may be
used for producing strips and arrays of collimating optical elements. The
lenses with embedded air voids enable compact designs of light modules
with multiple LEDs that can be combined into single integrated optical
elements as well as optical systems. For long or large optical assemblies
the invention provides a means of manufacturing without the often
prohibitively expensive tooling and equipment costs associated with large
injection molded optics. The accuracy of the method of the present
invention makes it suitable for not only the production of lenses in
lighting applications, but also optical elements utilizing TIR optics in
general.

[0045] With the improved manufacturing process, a cost-efficient way to
produce a wide range of optical elements and designs has been developed
by the system and method of the present invention.

[0046] FIG. 14 is an overhead view of an embodiment process configured for
high volume production whereby after exiting the extruder 30 the
workpiece 1 is heated to the annealing temperature, or annealing point,
of lens material if it is not already at that temperature or above. Upon
exiting the extruder 30, the workpiece 1 is at a certain temperature T1.
The surface of the workpiece, in accordance with an embodiment of the
present invention, must be heated above the annealing temperature of the
material for the workpiece to facilitate enabling the surface to be cut
without introducing surface stresses or altering the microstructure
undesirably. Typically annealing temperature ranges for acrylic, for
example, are between 85 and 160 degrees Celsius. While the surface of the
workpiece is at or above the annealing temperature, the surface may be
cut 10 by a high precision laser with a laser piece 21 in accordance with
the present invention, as shown in FIG. 13.

[0047] FIG. 15 is an exemplary flow chart illustrating an embodiment
method in developing and manufacturing collimating optical elements and
assemblies. The system is constructed in a modular fashion, and can
therefore be adopted and adapted in part depending on the application and
desired optical inputs and output from an optical assembly. Step 51)
establishes a lens design suitable for fabrication by the embodiment
fabrication method. Example designs are provided in this filing and many
more can be produced using principles of total internal reflection and
optical engineering. Snell's law is a fundamental physical law dictating
design of TIR optics. The embodiment method provides the ability to
easily integrate a specific given spatial distribution of multiple light
sources into a single optical element. This provides significant
convenience in the reuse of existing light source layouts to achieve new
light distribution outputs. Additionally overall performance advantages
can be achieved by allowing other factors such as thermal management to
be optimized by spatial layout with light sources subsequently integrated
mechanically and in optical mixing and output by designs of the
embodiment method.

[0048] Another step of the embodiment method flow charted in FIG. 15 is
step 50) to provide light transmissive matrix which serves as a substrate
for fabrication of an optical element. Acrylic and polycarbonate are
examples of common optically clear materials that may be utilized for the
production of optical elements. Depending on the application, one type of
material and manufacturing process may be more appropriate than another.
Although the system is found to be particularly advantageous in mass
production environments, all common molding processes may be used in the
first step of the process, including injection molding, compression
molding, and extrusion. Extrusion, for example, is a continuous
production method of manufacturing acrylic sheet that would be well
suited for the system and methods of the present invention, but it is no
so limited. In the process, pellets of resins are fed into an extruder
which heats them until they are a molten mass. This mass is then forced
through a die as a molten sheet. Subsequently, the molten sheet is fed to
calendar rolls, the spacing of which determine the thickness of the sheet
and in some cases the surface finish.

[0049] Another step of the embodiment method flow charted in FIG. 15 is
step 52) to create fabrication instructions for step 53) in the form of
software to control a localized subtractive process such as laser
cutting. Embodiments of this process step 52) have been realized in
practice by the use of a graphic software program combined with a
commercially available Legend CO2 laser system with print driver from
Epilog Laser Corporation of Golden, Colo. Other applicable software
solutions can be generated, for example by commercially available or
custom CAD or graphic arts software applications linked with laser print
drivers or CNC controllers. A CNC controller integrated with a 5-axis CO2
laser is particularly well suited for rapidly delivering and executing
laser cutting instructions where cuts at multiple angles of incidence to
a light transmissive substrate are required.

[0050] Another step of the embodiment method flow charted in FIG. 15 is
53) to fabricate an optical element with internally reflective walls by a
localized subtractive process. Step 53) uses instructions from step 52)
to control a localized subtractive process such as laser cutting to
fabricate air voids within the light transmissive matrix which
concurrently provide reflecting walls for total internal reflection
within the fabricated optical element. In a preferred embodiment, the
cutting of the light transmissive matrix material with a high precision
laser occurs while the material is at an annealing temperature which
limits the development of residual stresses in the optical element. This
is an advantage of the embodiment which can optionally be included in
step 53). The type of laser utilized in the present invention depends on
the material being cut. Said laser may for example be a CO2 or Fiber
laser. Part of step 53) may also optionally include further
post-processing operations employed to the workpiece, for example to
remove undesired surface characteristics or to produce hybrid optical
components. Cutting or trimming of the light transmissive sheet to a
desired part size can also be performed by a subtractive of step 53). The
lens may be cut of any length, large or small, an advantage of the
system. Cutting or trimming of a continuous web of light transmissive
sheet may be combined with the cutting of embedded reflecting walls
within step 53).

[0051] Steps 54) and 55) in the embodiment method flow charted in FIG. 15
test the performance of fabricated optical components and redirect the
process flow to reiterate portions of the overall process which need
improvement. Without the need for tooling to fabricate specific
reflecting wall designs, the process can be reiterated relatively quickly
thereby providing a rapid prototyping method. The overall benefits of the
embodiment method flow charted in FIG. 15 has been analyzed in comparison
to the an injection molding development and manufacturing method typical
of those used to develop and manufacture commercial collimating optical
elements and assemblies and the results are summarized in the table of
FIG. 17.

[0052] It will be understood that although the foregoing description
details designs, development methods, and manufacturing methods for
specific collimating optical assembly and optical element embodiments for
purposes of illustrating embodiments which may be used to advantage, it
is to be recognized that that the invention is not limited thereto.
Therefore, any and all variations and modifications that may occur to
those skilled in the applicable art are to be considered as being within
the scope and spirit of the invention.

Patent applications by Terence Yeo, Boston, MA US

Patent applications by FUSION OPTIX INC.

Patent applications in class Plural mirrors or reflecting surfaces

Patent applications in all subclasses Plural mirrors or reflecting surfaces